Many transport vehicles, such as tractor trailers or railway cars are equipped with tarp enclosures which provide total access to the interior of the vehicle. These tarp enclosures are usually supported by a framework which is mounted on rails or tracks which are secured to the lower side frame of the cargo bed of the vehicle and displaceable therealong. A problem with such displaceable wall sections is that the tarp is supported spaced from the lower side frame of the cargo bed whereby to permit a folding of the tarp in accordion fashion and also to prevent entanglement with the cargo bed or merchandise supported thereon. This spacing causes foreign matter such as water and dust to enter into the cargo space through the spacing between the lower section of the tarp and the cargo bed, and often causing damage to merchandise being transported in the cargo space. There is also a need to protect the rail on which these collapsible tarps are supported to prevent foreign matter from entering into the rail and causing the support wheels of the framework to jam or otherwise malfunction. During winter season, the roads on which the tractor trailers operate are often covered with salt calcium or chemical and sand mixtures whereby to melt the icy road surface and such product, in melted form, is sprayed onto these rails and in the crevices between the tarps and the frame by the wheels of the vehicle and wind thereby resulting in corrosion and malfunctions.